1. Field of the Invention
The present invention relates to forming of a photoresist pattern in the manufacturing of semiconductor devices such as IC and LSI, and in particular, to a defect correction process of photoresist patterns and an apparatus for correcting the defect of the pattern.
2. Description of the Prior Art
A typical conventional photoresist forming process in the manufacture of semiconductors and the like has been generally as shown in FIG. 1 (A) through (G). A substrate 10, which is the object of photoetching, consists of a base 11 and a film 12 to which a pattern is formed (refer to FIG. 1 (A)). The film 12 is first subjected to heat treatment so that the film may obtain highly adherent property to a photoresist of positive type and easy removing nature of adsorbates. Then, as shown in FIG. 1 (B), a photoresist layer 13 is applied over the film 12, and prebaking is performed to remove solvent remaining in the photoresist layer 13.
Then, as shown in FIG. 1 (C), exposure is performed through a suitable mask 14. When the photoresist layer 13 is of the negative type, a mask 14N is used (refer to FIG. 1 (D)). After the exposure, development is performed using a suitable solvent, and the photoresist layer 13 is formed corresponding to the pattern of the mask 14 (or the mask 14N) (refer to FIG. 1 (E)). Thereafter, post-baking is performed to strengthen the adherence between the photoresist layer 13 and the film 12, and the etching is further performed, with the resultant state as shown in FIG. 1 (F). As a remaining photoresist material is removed, the film 12 is eventually formed corresponding to the pattern of the mask 14 as shown in FIG. 1 (G).
If defects D1 through D5 as shown in FIG. 2 (A) exist in the photoresist pattern shown in FIG. 1 (E), defects E1 through E5 as shown in FIG. 2 (B) will appear in the pattern of the film 12. The presence of such defects E1 through E5 is not permissible in a substrate particularly when the substrate is to be used for a thermal head or a large area image sensor wherein the substrate has a large area and the whole area of the substrate works as a single functional element.
On the other hand, when the area of a device is large, it is likely that such defects E1 through E5 may appear anywhere, hence making it necessary to take a measure for correcting photoresist pattern to improve the yield of devices.
There have been proposed such measures as performing the photoresist pattern forming steps twice, making the positive type photoresist and the negative type resist two layers, and other methods. However, satisfactory correction for photoresist patterns has not been able to be made because no consideration has been given to the kinds of the defects D1 through D5 and the quantity of defects in such measures.